Structure and multiplicity of detonation regimes in heterogeneous hybrid mixtures

Veyssiere, B.; Khasainov, Boris

doi:10.1007/bf01414983

Cited by 25 publications

(9 citation statements)

References 9 publications

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“…Thus, the two-front structure here is not steady, in contrast to two-front steady-state detonation waves in reacting gases with monofuel particles studied in [18,19] and to hybrid detonation of gas suspensions [20,21]. Note that steady-state two-front structures in a bidisperse suspension of aluminum particles were not observed for any values of the mass fraction ratio in solutions of the steady-state problem and in steady-state solutions of initiation problems.…”

Section: Initiation Of Plane Waves In Bidisperse Suspensionscontrasting

confidence: 61%

Structure and initiation of plane detonation waves in a bidisperse gas suspension of aluminum particles

Федоров

Khmel

2008

Combust Explos Shock Waves

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Initiation and propagation of plane waves of heterogeneous detonation in a stoichiometric suspension of two fractions of aluminum particles in oxygen are analyzed numerically. It is found that the detonation is not ideal, and the steady-state part of the shock-wave structure is bounded by an equilibrium frozen sonic point. Initiation criteria depend on the particle-size distribution of the mixture. Initiation by explosive shock waves can lead to formation of unstable two-front structures. Addition of a small amount of fine particles into the discrete phase allows the initiation energy to be substantially reduced.

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Section: Initiation Of Plane Waves In Bidisperse Suspensionscontrasting

confidence: 61%

Structure and initiation of plane detonation waves in a bidisperse gas suspension of aluminum particles

Федоров

Khmel

2008

Combust Explos Shock Waves

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“…Interesting results were presented, e.g., by Borisov et al, 4 Fedorov et al, 14 and Ingignoli. 13 Khasainov and Veyssiére,15,16 Veyssiére and Khasainov,17,18 and Ingignoli 13 investigated the detonation in hybrid mixtures and confirmed that, depending on fuel concentration, the detonation wave can propagate in three different regimes.…”

mentioning

confidence: 77%

“…The ignition temperature is set to T ign = 1350 K, the decomposition temperature is equal to T dec = 3500 K, and the burning rate constant is K r = 4 × 10 6 s/m 2 . These values have been chosen arbitrarily based on previous works of Khasainov and Veyssiére, 15 Veyssiére and Khasainov,17,18 and Borisov et al 4 The computations are conducted on a uniformly spaced grid. The grid (cell) size is equal to 2 mm, and the detonation wave can propagate for 20 ms.…”

Section: Base Casementioning

confidence: 99%

Parametric Studies of an Aluminum Combustion Model for Simulations of Detonation Waves

Benkiewicz

Hayashi

2006

AIAA Journal

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We present a parametric analysis of a combustion model developed for computer simulations of detonation waves propagating in aluminum-dust-oxygen two-phase mixtures. In this model, consumption of solid and liquid aluminum is limited by its evaporation rate, and, depending on a gas-phase temperature, the fuel can be burned into aluminum oxide or aluminum monoxide. The model is applied for one-dimensional simulations of detonation waves. We analyze the influence of various factors on characteristic parameters of the detonation and compare computed results with those of other models and experimental data. The analyses show a qualitative agreement of the computed results with the Chapman-Jouguet detonation model. A combustion model and an initial solidphase concentration significantly influence the computed solutions. Specifically, a decomposition temperature has a strong effect on the system, because it limits the energy release in the combustion process. An initial particle diameter (with an exception of very fine dust) and an ignition temperature have no influence on the propagation of the detonation waves but are limiting factors for their development. Nomenclature B= universal gas constant C pk = kth species specific heat at constant pressure (k = 1, . . . , n s ) C vs = solid-phase specific heat C x = drag force coefficient c s = solid-phase concentration D = detonation wave velocity D CJ = Chapman-Jouguet detonation wave velocity d = average particle diameter d 0 = initial particle diameter E l = lth phase total specific energy (thermal and kinetic) e l = lth phase specific internal energy (thermal) (l = g, s, where g is gas and s is solid) F = vector of fluxes f = particle breakup (agglomeration) rate, 1/s h = interphase heat transfer factor kg/s 3 · m · K h f 298g k = kth species heat of formation h f 298s = solid-phase heat of formation K r = combustion rate constant, s/m 2 Ma = Mach number M g = average molar mass of gaseous mixture N p = particle number density, 1/m 3 N u = Nusselt number n s = species number p CJ = Chapman-Jouguet detonation pressure p g = gas pressure p vN = peak pressure (von Neumann spike) Re = Reynolds number S = vector of source terms T dec = aluminum oxide decomposition temperature T ign = ignition temperature= kth gaseous species mass fraction c = interphase mass exchange factor, kg/s · m 3 c k = kth species interphase mass exchange factor, kg/s · m 3 δ = interphase drag force factor, kg/s · m 3 λ g = gas-phase heat conduction coefficient π = 3.1415927 . . . ρ g k = kth species partial density ρ l = lth phase material density τ = characteristic combustion time φ s = solid-phase volume fractioṅ ω k = kth species production (consumption) rate due to homogeneous chemical reactions Subscripts CJ = Chapman-Jouguet point g = gas phase k = gaseous species index l = phase index s = solid phase vN = von Neumann spike

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“…Therefore, a higher heat capacity will lead to a lower second peak; this is also observed when the higher heat capacity is due to a larger particle diameter (6.0 lm). This ''double-front'' detonation was studied widely and its origin is attributed to the delayed combustion of the Al particle [41]. However, it is possible to form the second peak in an inert gas containing dust particles, due to the high particle concentration accumulated behind the initial detonation front [42].…”

Section: Discussion: Al-air Detonation Characteristicsmentioning

confidence: 99%

Numerical simulation of one-dimensional aluminum particle–air detonation with realistic heat capacities

Teng

Jiang²

2013

Combustion and Flame

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a b s t r a c t Aluminum (Al) particle-air detonation is very complicated because it includes multi-phase combustion phenomenon. Thus numerical simulations are often over-simplified. Here, the detonation is simulated by solving one-dimensional equations with more realistic heat capacities that vary with the dust mixture temperature. The effect on detonation parameters from the realistic heat capacities for the solid particles is investigated with a hybrid combustion model. The calculated results indicate that the detonation pressure, temperature and velocity vary significantly with changes in the heat capacity. Except for the velocity, these parameters are overestimated in numerical simulations when a constant heat capacity of the pre-shock mixtures is used. Furthermore, the realistic heat capacities have a strong effect on small diameter particles, but a weak effect on large diameter particles. Thus, when constant heat capacities are used, the combustion characteristic lengths are a function of the particle diameters with a power dependence of 1.77, whereas the power dependence decreases to 1.49 when realistic heat capacities are used. Moreover, if realistic heat capacities are applied, an ''abnormal'' strong detonation wave may appear in a dust mixture having large diameter particles. This phenomenon is consistent with the current combustion model, but it indicates that the value of heat released should also vary with the gas temperature in a fashion similar to that of the heat capacities.

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Structure and multiplicity of detonation regimes in heterogeneous hybrid mixtures

Cited by 25 publications

References 9 publications

Structure and initiation of plane detonation waves in a bidisperse gas suspension of aluminum particles

Structure and initiation of plane detonation waves in a bidisperse gas suspension of aluminum particles

Parametric Studies of an Aluminum Combustion Model for Simulations of Detonation Waves

Numerical simulation of one-dimensional aluminum particle–air detonation with realistic heat capacities

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